Lord Ashcroft seemed to be relishing the prospect of documenting Cameron’s demise.
Photograph: Christopher Thomond for the Guardian

In January, four months before the general election, Lord Ashcroft assumed he was writing the prime minister’s political epitaph. The Conservatives were heading for possible defeat and the former deputy party chairman who helped propel David Cameron into Downing Street in 2010, told a book awards audience: “As most of you know we are writing the obit … Ah sorry David, the biography.”

The billionaire Tory donor who had given his party £8m, felt strongly he had been spurned over a senior job and his joke suggested he might be relishing documenting Cameron’s demise.

But now instead of reading the last rites, Ashcroft’s unofficial biography of the PM, Call Me Dave, is being published as Cameron heads triumphantly towards party’s autumn party conference in Manchester with a mandate for another five years in power. Rather than an obituary, Ashcroft’s book bears the hallmarks of a revenge job, and a gory one at that.

Extracts published in the Daily Mail on Monday included claims the prime minister stuck “a private part of his anatomy” in a pig’s mouth in a student initiation ceremony at Oxford, smoked pot and listened to Supertramp records in a student friend’s room and allowed cocaine to be used at dinner parties at his home. Downing Street said it would not dignify Ashcroft’s allegations by offering any comment.

Only a few years ago, Ashcroft was inside Conservative central office using his fortune to help Cameron’s party target dozens of crucial marginal seats. On Tuesday more revelations are promised about Cameron’s “links to the Chipping Norton set” in a serialisation understood to have cost the newspaper well over £50,000.

Ashcroft, whose company Political Holdings Limited is the majority shareholder in the book’s publisher Biteback, has insisted his work would be objective and “not about settling scores”. His co-author, Isabel Oakeshott, the former Sunday Times political editor, said on Monday: “If this was just a revenge job then Lord Ashcroft and I could have published it before the election and that could have caused far more damage.”

Cameron is under pressure over his university days in Lord Ashcrofts new book with claims emerging a sex act with dead pig. Photograph: Andy Rain/EPA

But as well as the highly embarrassing claims about the PM, the Tory peer also sets out in the clearest terms yet his falling out with the PM. He was in Gallipoli on Monday visiting first world war battlefields, but tweeted the foreword of his book, which sets out in detail how he was disappointed by Cameron’s failure to offer him a significant job in government and implied that he thinks Cameron had broken his word. Ashcroft complained he was offered nothing more by Cameron than a role as a junior whip in the Foreign Office, which he turned down.

One rival newspaper executive described the serialisation and timing as a “declaration of war” by the paper’s editor-in-chief, Paul Dacre, on Cameron, who he believes is too soft on serious issues such as immigration and Europe. A spokesperson for the paper said it was “a hugely anticipated and important biography”.

However, even the authors concede the claim that has most captured public interest, about the pig, comes from only a single source. They said the claim was made by an MP, who had pointed them towards another individual who supposedly had a photograph of the incident, although this person never responded to their approaches. Ashcroft and Oakeshott concluded: “Perhaps it is a case of mistaken identity.”

Ashcroft began work on the book in earnest three years into the coalition government, when he poached Oakeshott from the Sunday Times. “When this project was conceived,” he said in the foreword, “it seemed possible that the outcome of the 2015 election would mark the end of Cameron’s tenure at Downing Street.”

He gave a hint of his motivation when Cameron reshuffled his cabinet in July 2014 and William Hague stood down from his role. Ashcroft tweeted “Standing by to take over as foreign secretary . . .”

The next day, he wrote: “No call from No 10! Ah well . . . back to the biography of Cameron … any anecdotes or stories to follow up welcome.”

Oakeshott, who lives part of the time in the Cotswolds close to Cameron’s constituency home, threw herself into the task. When the prime minister took part in the annual Great Brook Run, a mile-long race through a shallow stretch of the Evenlode river in January this year, she donned her running kit and followed Cameron and his security detail through the icy water. Cameron said to her: “The things you’ll do for this book.” MPs and Cameron’s former student friends were persuaded to talk on and off the record.

As they progressed, Ashcroft and Oakeshott gave teasing glimpses into their research. Cameron spent time in Russia before going to university and claimed when he appeared on Desert Island Discs that the KGB tried to recruit him.

Was it this the writers were researching as they posed for pictures in front of the VIP terminal at Sochi international airport in Russia and outside the Duma, parliament in Moscow? Either way, they seemed to be enjoying their work. Oakeshott posted pictures inside a luxurious Moscow restaurant featuring a bathtub filled with bottles of champagne and later one from Centre Court at Wimbledon. In September, she tweeted: “It’s a pleasure working for the ‘evil’ one @LordAshcroft.”

“There is a side of him that enjoys mischief,” a source close to Ashcroft said on Monday. “He has a dry sense of humour. Some people [at Conservative campaign headquarters] used to refer to him as Blofeld [the Bond villain] and he liked that.”

Downing Street’s response to the project is understood to have been overseen by Craig Oliver, Cameron’s communications chief. He is said to have consulted Boris Johnson, whose own time as a member of the Bullingdon Club at Oxford has been widely exposed.

Downing Street decided not to cooperate while Johnson did, although his approach was to provide testimony that was supportive of Cameron. Cameron himself “privately discouraged Oakeshott from getting involved, warning that she would get caught in crossfire between us”, Ashcroft said.

“Cameron is suspicious,”, the peer reported in April in a blog. “It is no secret that he dislikes the prospect of what he dismissively labels ‘the Ashcroft book’. We have tried, and failed, to persuade him to talk.”

He complained that Anthony Seldon, political historian and former headmaster of Wellington College, who also published a book about Cameron’s premiership this month, was granted co-operation from Downing Street, including from Ed Llewelyn, Cameron’s chief of staff.

“The prime minister has shut the doors to us,” Ashcroft said. “Letters to relatives requesting interviews have gone unanswered, and senior aides know he does not want them to help. Some individuals who were willing to talk to us in principle but wanted Downing Street’s blessing were repeatedly stonewalled. Cameron’s strategy appears to be: put up the shutters, then rubbish the book on the basis that we have had no access.”

According to a party insider, Cameron and Ashcroft used to get on relatively well. Ashcroft had a closer relationship with William Hague, under whose party leadership he acted as Conservative treasurer, but considered the new leader a better prospect than his predecessor, Michael Howard, had been.

“David was following a strategic direction that was much closer to ‘Smell the Coffee’ [Ashcroft’s study of how the Tories had lost the 2005 election under Howard],” the source said. “But there was never the personal closeness there was with Hague.”

As the 2010 election approached, press and opposition interest grew about Ashcroft’s tax status and Cameron and Ashcroft discussed how they could delay revealing he was a non dom until after the election, Ashcroft writes. Ashcroft now claims he told Cameron of his statement in 2009, whereas Cameron has said he did not know about this until 2010.

He also said that ahead of the 2010 election he and Cameron discussed “the type of role I would take were he to become prime minister” but that when the election was won, no job offer came, even when Ashcroft explicitly asked. He said his “uneasy” and “somewhat strained” relationship with Cameron dates back to this time.

He wrote: “Once he became prime minister I waited, as many do, for the telephone call. After hearing nothing for a couple of days, I spoke to Andrew Feldman, who was co-chairman of the party. Shortly afterwards Cameron called me, to thank me profusely for all the work that I had done. I thanked him in turn and asked what my next role would be. There was silence at the end of the phone. ‘Ah, it’s difficult,’ he replied awkwardly. ‘We probably need to have another conversation.’ He left me hanging.”

Cameron then invited him to lunch at Chequers, took him for a walk and claimed Nick Clegg, the deputy prime minister, had vetoed his appointment, which he said he later checked with Clegg’s office and found out not to have been true.

Ashcroft concluded: “I could not help but reflect on a comment made to me by a shadow cabinet minister in the runup to the 2010 election that Cameron’s word is as good as the paper it’s written on.”

One Conservative pointed out that the impact of Ashcroft’s claims about Cameron’s early life was affected by his admission that he felt wronged by him.

“However sensational the claims he makes, it is undercut by the fact that he is so upfront about his dislike for Dave,” they said. “It may well be true [that Ashcroft was bitter about being overlooked for a political post] but doesn’t that overshadow everything you then write?”

Ashcroft has promised to update the book and has said that he made “full and contemporaneous notes” of his discussion with Cameron about his future role in government and how it would be “not an insignificant” position. He has promised to provide detail of all that in his eventual autobiography.